Fix gas estimation (#1944)

* Fix gas estimation for threshold > 4

* Update gas estimation to be more precise

* Add threshold gas costs on transaction creation estimation

Co-authored-by: Daniel Sanchez <daniel.sanchez@gnosis.pm>

src/logic/hooks/useEstimateTransactionGas.tsx

@@ -5,6 +5,7 @@ import {
   estimateGasForTransactionCreation,
   estimateGasForTransactionExecution,
   MINIMUM_TRANSACTION_GAS,
+  GAS_REQUIRED_PER_SIGNATURE,
 } from 'src/logic/safe/transactions/gas'
 import { fromTokenUnit } from 'src/logic/tokens/utils/humanReadableValue'
 import { formatAmount } from 'src/logic/tokens/utils/formatAmount'
@@ -229,12 +230,13 @@ export const useEstimateTransactionGas = ({
           safeTxGas,
           approvalAndExecution,
         })
+
         const gasPrice = manualGasPrice ? web3.utils.toWei(manualGasPrice, 'gwei') : await calculateGasPrice()
         const gasPriceFormatted = web3.utils.fromWei(gasPrice, 'gwei')
         const estimatedGasCosts = gasEstimation * parseInt(gasPrice, 10)
         const gasCost = fromTokenUnit(estimatedGasCosts, nativeCoin.decimals)
         const gasCostFormatted = formatAmount(gasCost)
-        const gasLimit = (gasEstimation * 2 + MINIMUM_TRANSACTION_GAS).toString()
+        const gasLimit = (gasEstimation * 2).toString()
 
         let txEstimationExecutionStatus = EstimationStatus.SUCCESS
 
@@ -257,7 +259,7 @@ export const useEstimateTransactionGas = ({
       } catch (error) {
         console.warn(error.message)
         // We put a fixed the amount of gas to let the user try to execute the tx, but it's not accurate so it will probably fail
-        const gasEstimation = MINIMUM_TRANSACTION_GAS
+        const gasEstimation = MINIMUM_TRANSACTION_GAS + (threshold || 1) * GAS_REQUIRED_PER_SIGNATURE
         const gasCost = fromTokenUnit(gasEstimation, nativeCoin.decimals)
         const gasCostFormatted = formatAmount(gasCost)
         setGasEstimation({

src/logic/safe/transactions/gas.ts

@@ -1,4 +1,5 @@
 import { BigNumber } from 'bignumber.js'
+
 import { getGnosisSafeInstanceAt } from 'src/logic/contracts/safeContracts'
 import { calculateGasOf, EMPTY_DATA } from 'src/logic/wallets/ethTransactions'
 import { getWeb3, web3ReadOnly } from 'src/logic/wallets/getWeb3'
@@ -12,6 +13,8 @@ import { sameString } from 'src/utils/strings'
 
 // 21000 - additional gas costs (e.g. base tx costs, transfer costs)
 export const MINIMUM_TRANSACTION_GAS = 21000
+// Estimation of gas required for each signature (aproximately 7800, roundup to 8000)
+export const GAS_REQUIRED_PER_SIGNATURE = 8000
 
 // Receives the response data of the safe method requiredTxGas() and parses it to get the gas amount
 const parseRequiredTxGasResponse = (data: string): number => {
@@ -177,9 +180,10 @@ const calculateMinimumGasForTransaction = async (
   estimateData: string,
   txGasEstimation: number,
   dataGasEstimation: number,
+  fixedGasCosts: number,
 ): Promise<number> => {
   for (const additionalGas of additionalGasBatches) {
-    const amountOfGasToTryTx = txGasEstimation + dataGasEstimation + additionalGas
+    const amountOfGasToTryTx = txGasEstimation + dataGasEstimation + fixedGasCosts + additionalGas
     console.info(`Estimating transaction creation with gas amount: ${amountOfGasToTryTx}`)
     try {
       const estimation = await getGasEstimationTxResponse({
@@ -224,7 +228,13 @@ export const estimateGasForTransactionCreation = async (
       return gasEstimationResponse
     }
 
+    const threshold = await safeInstance.methods.getThreshold().call()
+
     const dataGasEstimation = parseRequiredTxGasResponse(estimateData)
+    // We add the minimum required gas for a transaction
+    // TODO: This fix will be more accurate when we have a service for estimation.
+    // This fix takes the safe threshold and multiplies it by GAS_REQUIRED_PER_SIGNATURE.
+    const fixedGasCosts = MINIMUM_TRANSACTION_GAS + (Number(threshold) || 1) * GAS_REQUIRED_PER_SIGNATURE
     const additionalGasBatches = [0, 10000, 20000, 40000, 80000, 160000, 320000, 640000, 1280000, 2560000, 5120000]
 
     return await calculateMinimumGasForTransaction(
@@ -233,6 +243,7 @@ export const estimateGasForTransactionCreation = async (
       estimateData,
       gasEstimationResponse,
       dataGasEstimation,
+      fixedGasCosts,
     )
   } catch (error) {
     console.info('Error calculating tx gas estimation', error.message)